The present invention relates to batteries, and more specifically, to extending the functionality of a battery.
Batteries are used for many functions, to power portable computers, provide backup power, and power all types of portable devices. However, batteries have a limited lifetime. After a period of use, most rechargeable batteries develop xe2x80x9cvoltage depression,xe2x80x9d which results in the battery run-time decreasing after each recharge.
FIG. 1 illustrates a prior art voltage curve, for a new battery 110 and an old battery 120. The turn-off voltage 130 is set, for example for a camcorder, at a level below the level of the fully charged battery. Thus, a new battery, as can be seen, takes an hour to reach the turn-off voltage 130. However, an old battery 120 drops down more rapidly, to reach the turn-off voltage 130 after a mere 2.5 minutes. Thus, the old battery cannot be used to power devices, since the useable time is minimal.
The prior art to reduce the xe2x80x9cmemoryxe2x80x9d effect has been to deep discharge the batteries, typically at a current discharge rate well below the normal operating current level for a given application. Neither the battery run time or lifetime is enhanced by this. In addition, the standard practice of discharging a rechargeable battery down only to about 1.12 volts, which is considered the fully discharged level for new batteries, contributes directly to the battery xe2x80x9cmemoryxe2x80x9d phenomenon where older batteries have greatly reduced run time.
A method to extend the functionality of a battery, the method comprising drawing power from the battery, and repetitively drawing a current pulse greater than the minimum conditioning current from the battery, thereby conditioning the battery.